Use of aqueous binders in producing filter materials

Abstract

The use of an aqueous polymer dispersion comprising dispersed particles of at least one polymer A1 obtainable by free-radical emulsion polymerization in the presence of a polymer A2 synthesized from from 50 to 99.5% by weight of at least one ethylenically unsaturated monocarboxylic and/or dicarboxylic acid, from 0.5 to 50% by weight of at least one ethylenically unsaturated compound selected from the esters of ethylenically unsaturated monocarboxylic acids and the monoesters and diesters of ethylenically unsaturated dicarboxylic acids with an amine containing at least one hydroxyl group, up to 20% by weight of at least one further monomer as a binder for producing filter materials.

1. A filter material treatment process comprising:
 resinating a filter material with an aqueous polymer dispersion comprising dispersed particles of at least one polymer A1 obtained by free-radical emulsion polymerization in the presence of a polymer A2 to form a resinated filter material, and 
 curing the resinated filter material; 
 wherein the polymer A2 comprises: 
 (i) polymerized units of from 50 to 99.5% by weight of at least one of an ethylenically unsaturated monocarboxylic acid and an ethylenically unsaturated dicarboxylic acid, 
 (ii) from 0.5 to 50% by weight of at least one ethylenically unsaturated compound having an amine containing at least one hydroxyl group selected from the group consisting of an ester of an ethylenically unsaturated monocarboxylic acid, a monoester of an ethylenically unsaturated dicarboxylic acid, and a diester of an ethylenically unsaturated dicarboxylic acid, and 
 (iii) up to 20% by weight of at least one further monomer. 
 
     
     
       2. The process of  claim 1 , wherein the curing is carried out by heating the resinated filter material. 
     
     
       3. The process of  claim 2 , wherein the heating is carried out at a temperature of from 100 to 250° C. for from 0.1 to 60 minutes. 
     
     
       4. The process of  claim 1 , wherein the filter material is a filter paper or a filter cloth. 
     
     
       5. The process of  claim 1 , wherein the pH of the aqueous polymer dispersion is from 2 to 8. 
     
     
       6. The process of  claim 1 , wherein the pH of the aqueous polymer dispersion is from 3.0 to 6.5. 
     
     
       7. The process of  claim 1 , wherein the aqueous polymer dispersion further comprises a base. 
     
     
       8. The process of  claim 1 , wherein the pore size of the filter material and the cured, resinated filter material is the same. 
     
     
       9. The process of  claim 1 , wherein the air permeability of the filter material measured by ISO 9237 does not decrease by more than 13% after the resinating and the curing. 
     
     
       10. The process of  claim 1 , wherein the permeability of the filter material measured by ISO 9237 does not decrease by more than 1% after the resinating and the curing. 
     
     
       11. The process of  claim 1 , wherein the permeability of the filter material measured by ISO 9237 does not decrease by more than 4% after the resinating and the curing. 
     
     
       12. The process of  claim 1 , wherein the resinating is carried out in the absence of organic solvents. 
     
     
       13. The process of  claim 1 , wherein the polymer A2 comprises polymerized units of at least one of an ethylenically unsaturated monocarboxylic acid and an ethylenically unsaturated dicarboxylic acid; and at least one compound selected from the group consisting of a C 3 –C 10  monocarboxylic acid and a C 4 –C 8  dicarboxylic acid. 
     
     
       14. The process of  claim 1 , wherein the polymer A2 comprises at least one ethylenically unsaturated compound having an amine containing at least one hydroxyl group selected from the group consisting of a monoester of an ethylenically unsaturated dicarboxylic acid with an amine and a diester of an ethylenic ally unsaturated dicarboxylic acid,
 wherein the amine containing at least one hydroxyl group is at least one amine of formula (I):
   R c NR a R b   (I) 
 
 wherein R c  is at least one of a C 6  to C 22  alkyl, a C 6  to C 22  alkenyl, an aryl-C 6 –C 22  alkyl or an aryl-C 6 –C 22  alkenyl, wherein the alkenyl radical may have 1, 2 or 3 nonadjacent double bonds, 
 R a  is at least one of a hydroxy-C 1 –C 6  alkyl or a radical of formula II
   —(CH 3 CH 2 O) x (CH 2 CH(CH 3 )O) y —H  II 
 
 wherein the sequence of the alkylene oxide units is arbitrary and x and y independently are an integer from 0 to 100, and the sum of x and y is >1, 
 R b  is at least one of hydrogen, a C 1  to C 22  alkyl, a hydroxy-C 1 –C 6  alkyl, a C 6  to C 22  alkenyl, an aryl-C 6 –C 22  alkyl, an aryl-C 6 –C 22  alkenyl or C 5  to C 8  cycloalkyl, wherein the alkenyl radical may have 1, 2 or 3 nonadjacent double bonds, or R b  is a radical of formula III
   —(CH 2 CH 2 O) v (CH 2 CH(CH 3 )O) w —H  (III) 
 
 wherein the sequence of the alkylene oxide units is arbitrary and v and w independently are an integer from 0 to 100. 
 
     
     
       15. The process of  claim 1 , wherein the weight ratio of polymer A1 to polymer A2 based on the solid weight of polymer A1 and polymer A2 is from 9:1 to 1:9. 
     
     
       16. The process of  claim 1 , wherein the weight ratio of polymer A1 to polymer A2 based on the solid weight of polymer A1 and polymer A2 is from 3:1 to 1:3. 
     
     
       17. The process of  claim 1 , wherein the aqueous polymer dispersion further comprises an alkanolamine crosslinker having at least two hydroxyl groups. 
     
     
       18. The process of  claim 1 , wherein the aqueous polymer dispersion comprises an inorganic component. 
     
     
       19. The process of  claim 1 , wherein the resinating is carried out by impregnating the filter material with the aqueous polymer dispersion. 
     
     
       20. The process of  claim 1 , wherein the resinating is carried out by spraying the aqueous polymer dispersion onto the filter material. 
     
     
       21. A resinated, cured filter material obtained by the process as claimed in  claim 1 . 
     
     
       22. The process of  claim 1 , further comprising:
 passing a particulate-containing fluid through the cured, resinated filter material to remove the particulate from the fluid and provide a filtered fluid.